Tri Nguyen

I make websites and web applications. Simple and minimal interfaces make me happy.

Surprised that there was no built-in authentication mechanism for Google Cloud Functions, I made an attempt to implement a simple one with JWT and Auth0

With all the hype around serverless, I recently took a stab at creating a cloud function and see how it goes. I went with Google Cloud Functions instead of AWS Lambda, because I had some free signup credits on Google.

However, it soon dawned on me that this is pretty insecure, as anyone who knows of this endpoint could write to the database. Imagine if I wrote a delete function! I thought surely Google must have built in some sort of authentication scheme for Cloud Functions. But after googling around for a while, it didn’t seem so. I did next what any clueless developer would, and post a question on StackOverflow.

After a few days, the answers I got back seemed pretty disappointing. Apparently if I had used AWS Lambda, I could leverage API Gateway, which has support for auth. But I am on my own for Google Cloud Functions.

So I decided to implement an authentication check for my cloud function with a JWT token passed in in the form of an Authorization header access token, with the help of Auth0.

I use jwks-rsa to retrieve the public key part of the key that was used to sign the JWT token, and jsonwebtoken to decode and verify the token. I use Auth0, so jwks-rsa reaches out to the list of public keys to retrieve them.

The checkAuth function can then be used to safeguard the cloud function as:

This has been one of the hardest/ most terrifying decisions for me to make: leave a growing career at Demandware/ Salesforce Commerce Cloud and come to New York City and work for Bloomberg.

Now that I’ve been in New York for a few months, I’d like to jot down a few thoughts, so that I could look back on at some point in the future.

One of the biggest reasons for leaving was to grow my career as a technical person. I was doing really well at Demandware, and I was getting comfortable. It is a great spot to be in. However, drawing from past experience, I figured that the most growth I undergo comes from putting myself in unfamiliar/ uncomfortable position. It’s hard. It sucks. And as the last few months of being in NYC indicates, it really does suck. But, I have also grown. I have been exposed to more technologies and more interesting ways of solving problems.

I had to restart my PERM application process all over again. At the time, I figured this would be a good thing – I still have enough buffer time to do so. Looking back, I think perhaps it might have been wiser to stay on for another couple years and complete that.

Another reason was for Mark and I to experience a new lifestyle. Being in a big city, using public transportation, and most importantly, being more active with easier access to walking/ biking. This has been true. We do enjoy the new lifestyle. On the other hand, it has been dampened by the frustration of Mark’s job seeking process. Hopefully, this is only a temporary setback.

My parents are coming to visit for an extended period of time again this year. I’d like to be in a place where they can get out of the house on their own and explore. It seems like it shouldn’t be a factor in such a life-changing decision, but if I were honest with myself, I think this is definitely one of the reasons. After being away from home for 12+ years, I’d like to spend more quality time with them.

After being at Demandware for 3 years, I started to feel like I wasn’t progressing fast enough towards my career goals of being more involved in architecting applications (technical) and in building up teams (non-technical). I understood that I was (and still am) relatively inexperienced in either of those things. From the little I could deduce, those roles require more varied background and experiences. The role at Bloomberg isn’t exactly the big next step up, but I decided to make a leap of faith, hoping that it will add to the diversity of my experiences. This could turn out to be a mistake, who knows. After sharing my decision with the management at Demandware, it seemed like I had a chance to make a shortcut towards my goals with the company. That seemed like too little too late, and given the other reasons, I decided to let go of the leverage and made the jump.

At this juncture, looking back, it is still a toss-up whether this decision has turned out to be the right one. I am going through a lot of challenges, both personally and professionally, that make me constantly question the move. I hope that in a year or so, the outlook on things will improve. I knew that it was a long-term investment that would require a bit of short-term pain. I should try to stay positive and see the rewards.

I was unaware of the difference between static linking and dynamic linking in linux. Thankfully Ben Kelly explained to me in some details these concepts on a Slack chat. I wanted to document them here for future references.

Static linking: when you link the program (the step after compilation that combines all the compiler outputs into a single runnable program), the linker tracks down the libraries the program needs and copies them into the final program file.

Dynamic linking: at link time, the linker merely records which libraries are needed, and when you run the program, the “dynamic linker” reads that information and runs around loading those libraries into memory and making them accessible to the program.

Advantage of the latter is smaller (potentially *much* smaller programs) and you can upgrade the libraries without rebuilding everything that uses them. Disadvantage is that those upgrades can break compatibility, and it’s another external dependency for the program (and thus another point of failure).

The dynamic linker has a bunch of ways it figures out where the libraries are stored; `man ld.so` for all the gory details.

But the tl;dr is that it has a few system paths it looks in (typically /lib and /usr/lib), plus whatever is listed in the environment variable LD_LIBRARY_PATH, plus whatever is recorded as the “rpath” in the executable itself.

1. It makes it more difficult to understand during debugging how execution arrived at a certain point since the stack contains discontinuities and
2. Error.prototype.stack contains less information about execution flow which may break telemetry software that collects and analyzes client-side errors.

A note about the terminology: when learning about this, another term is also used to describe PTC, i.e. tail call optimization (CTO). I think that PTC is preferred, as it should be a mandatory feature, as it is currently spec-ed in ES6, and not an optional optimization. See this tweet .

tesseraic, an engineer at Apple, has been incredibly helpful in pointing me to some of these resources and explaining the concept in more details.